1. Field
One or more embodiments of the present invention relates to a secondary battery and a secondary battery module including the same.
2. Description of the Related Art
A secondary battery, unlike a primary battery, is rechargeable. As such, secondary batteries are often used as a power source for small electronic apparatuses such as, for example, mobile devices. In addition, secondary battery can also be used as a power source for driving a motor of a hybrid vehicle.
A typical secondary battery includes an electrode assembly, a battery case for accommodating the electrode assembly, and a cap assembly for covering an opening of the battery case. The electrode assembly is electrically coupled to an external power source device through a positive electrode terminal and a negative electrode terminal of the cap assembly.
The positive electrode terminal and the negative electrode terminal can also be electrically coupled to a negative electrode terminal and a positive electrode terminal of another secondary battery through a bus bar.
The terminals and the bus bar are usually coupled through welding. However, a material of the terminals and that of the bus bar are often different metal materials. The quality of welding of dissimilar metals is lower than the quality of welding of similar metals. As a result, welding bond strength between the terminals and the bus bar is lower than it would have been if the terminals and the bus bar were formed of the same material.